Self-shifting track



H. 1. BENTSON.

SELF SHN-' TING TRACK. APPLICATION FILED MAY31, 1919.

Patented July 4, 1922. l

2 SHEETS-SHEET l.

H. J. BENTSON.

SELF SHIFTlNG TRACK.

APPLlcATxoN man MAY 31, 1919. 1,421,387, I Patented July 4, 1922. A 2 SHEETS-SHEET 2.

HANS J'. BENTSON, OF WINTHROP HARBOR, ILLINOIS, ASSIGNOR TO FREDERICK C.

AUSTIN, 0F CHICAGO, ILLINOIS. f

SELF-SHIFTING TRACK.

Application filed May 31, 1919.

To all whom t may concern Be it known that I, HANs J. BnNrsoN, a citizen of the United Statesof America, and a resident of Winthrop Harbor, Illinois, have invented a certain new and useful Improvement in Self-Shifting Tracks, of which the following is a specification.

This invention relates to meansv for supporting heavy machines, such as excavators, on the ground, so that the machine may be moved forward from time to time, and relates more particularly to means of this kind involving tracks upon which the wheels vof the machine travel, and which are shifted ahead periodically, whereby the wheels `will always have a smooth track upon which to travel.

Generally stated, the object of the invention isto provide a novel and improved construction and arrangement whereby the tracks are automatically shifted forward from time to time, as the machine travels along, so that no special attention is necessary for these tracks, and no control thereof by the attendant, each track being automatically shifted forward as soon as the weight is removed therefrom and as soon as the weight is imposed on the other track, thus obviating the necessity of employing any special means for shifting the tracks when it is desired to move the machine forward,

It is also an object to provide certain details and features of construction yand combinations tending to increase the general efficiency and the desirability of a shifting track arrangement of this particu` lar character.v

To these and other useful ends the `invention consists in matters hereinafter set forth and claimed, and shown in the accompanying drawings in which'* Fig. l is a sideY elevation ofthebody of an excavator or other heavy machine, showing the samev equipped with .an automatic shifting track arrangement embodying the principles of the invention.

ig. 2 is a longitudinal section of said machine, on a line extending .through one of the tracks.

Fig. 3 is a plan of the Vstructure'Shown in Fig. l.

Specification of Letters Patent. l

Patented July a, i922. Serial No. 300,820.

Fig. 4 is a horizontal section on line 4 4 in Fig. l.

Fig. 5 is a similar view showing the tracks in'a different position-that is to say, showing one track shifted forward.

Fig. 6 is a detail section on line 6 6 in Fig. 2. V

Fig. 7 is a perspective of one of the pairs of segmental or half-round wheels which travel on the tracks.

As thus illustrated,'the body l of the excavator or other heavy machine, may be of any suitable form or character, and in the drawings only one side of this body is shown, it being understood that the other side would 'be equipped with a shifting track arrangement of similar character. The body is provided with axles 2, each axle having a pair ofwheels 3 and 4 fixed thereon, 'and each wheel being only half round7 so that the weight is first supported by one wheel and then' the other,`as the two wheels are oppositely disposed on the axle. The outer wheels 3 travel on a track 5, and the inner wheels 4 travel on a similar track 6, the two tracks being arranged parallel and 'provided with grooves to prevent the wheels from running 0H. It will be-seen that all Vof the wheels are so arranged on their axles that the wheels 3 strike the track 5 at the same time, and thus supportthe weight, and that the wheels 4 operate similarly on the track 6, thus shifting the weight alternately from one track to thefothen The axles are all connected together by sprocket chains 7, or by `any suitable means, so that the relative'pos'- tions of the wheels willbe 'maintained as 90 the machine travels along. Driving power is communicated to said wheels from an en` gine 8, or from any other suitable source, for example, through the medium of a sprocket chain 9 extending to a sprocket 95 wheel on one of said axles.

The means for' shifting the tracks is as follows: The two tracks have their ends connected together by a flexible connection 10 ext-ending. around a sheave 11, which latter is connected to the body frame through the medium of a spring l2, this arrangement being employed at both the front and the rear ends of the machine, so that the machine by direct contact of the wheels interruption `for `any 'to the other, so `nately relieved `of weight rand leased, and instrumentalities machine can travel in either direction. As shown in Fig. 4, the weight is being imposed upon the track 5, and is being taken off of the track 6, and as soon as the wheels 4 leave the track 6, the forward motion of the `machine will then pull this track 6 forward in the manner shown in Fig. 5. Of course, while the weight is being; shifted from one set of wheels to the other, there is a time when the weight is on both tracks, momentarily Vat least, and during' suoli time the two tracks are stationary. It is :for this purpose, therefore, that the springs 12 are employed-that Ais to say, Athey i permit the forward movement of the body frame 4while both ftracks remain stationary, `but as soon as one `ltrack isreleaserh Vthe tension of the spring which has ibeen stretched `will jerk the released track iforward, fand this track will then be pulled along further by the continued forward movement of the body frame. In Ythis way, each 4.track balances the other, so to speak, and the f-tracks are alternatelyshifted forward automatically, it'will be seen, Lmerel-v by the `forward motion of the body frame. No special attention is necessary "for the shifting` of the tracks, and no power other than that furnished by the forward movement `of the body frame itself, is necessary for 4the shifting of the Asmooth path of travel is Yprovided for the wheelsof the machine to travel upon, so that a machine 1of great `weight `may travel across `soft `ground or over places where it would `be impossible to support the thereof with the ground. The tracks, however, simply take care of themselves, as they are dependent merely upon the forward motion of the entire machine for the shifting df first one track and then the other.

`By reasonof the sheaves ll1, and the flexible connections 1Q extending around each sheave, in the ymanner shown, it is obvious that `each track when released will travel `forward faster than the body frame, its speed of forward movement being substantially twice `that of ithe body frame. In` effect, each track, when held stationary by the weight imposed thereon, `serves "to pull they other track forward, and this action is adapted to `continue smoothly and without length of time, while the macliineis travelling' steadily forward.

What 1' claim `as my invention is 1. The combination .of a body provided with segmental wheels, tracks resting on the Vground to support said wheels, .means `,for

causing,` forward movement `of said body, so that the wheels will `roll along upon "said tracks, `said wheels "being adapted to shift the `load weight :alternately from one track that the tracks are alterthereby Vredependent upon the forward motion of the body and operated thereby to automatically and alternately pull the tracks directly forward along the ground.

2. A structure as specified in claim l, said instrumentalities comprising a sheave connected to the body, and a flexible connection attached to the tracks and extending .around said sheave, so that either track when released will travel forward faster than the body.

3. A `structure las specified in claim l, said instrumentalities comprising a sheave, means including a spring `for connecting the sheave to the body, and a flexible connection attached to thetracks and extending,- around the sheave.

a. A structure as specified in claim 1, said instrumentalities being operative ,to shift the tracks by either the forward or the backward `movement of the body.

5. A structure as 'specified in claim 11, said instrumentalities 'comprising a, spring to permit forward movement ofthe"bodywhile both tracks remain stationary on'the ground, and while'the `two tracks momentarily both support the weight of the body, and ,before one track-is released by the shifting of the weight therefrom `to `the other track.

6. The combination of a body, supportingwheels `for said body,^`tracks for said wheels, said wheels being; adapted toalternately shift the load weight from one track to the other, a power plant on thefbody tov operate said wheels, thereby to propel the 'body forward, and means whereby either track when released is shifted directly forward from its lload sustaining position 'by the forward motion of the body, so that said source of power serves `not only to propelthe body forward on `the tracks, butV serves also by the `forward motion of the body to propel the tracks forward.

either `track when released to travel forward fasterthanthebody.

v9. The combination ofia body frame, segmental wheels for said fra-me, tracks supported on. .the ground for said wheels,'and

by the motion of the frame, said connections having oneor more springs to permit one or more of the tracks to remain stationary while the load weight of the forwardly moving body frame issustained thereon.

'1 0. The combination of a pair of tracks, a body frame having half-round wheels to fdirect connections between the tracks and p the body frame to pull the tracks forward travel on said tracks, and means for automatically pulling the tracks forward, having provisions for equalizing the pull on the two tracks.

l1. The combination of a pair of tracks, a body frame having wheels to travel on said tracks, adapted to alternately shift the load weight from one track to the other, and

connecting means extending between the body frame and the tracks for automatically pulling the tracks alternately forward, having provisions to equalize the forward pull on said tracks, so that either track must remain stationary to cause the forward movement of the other track.

HANS J. BENTSON. 

